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You have some energy production (typically solar panels).
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You want to self-consume as much as possible of this energy.
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You have a device (typically a water heater) which could consume the part of the energy, which would otherwise be injected into the public electricity grid.
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You have an energy meter which measures the power consumed by your household (typically a Shelly EM). The power can be either positive (power is consumed) or negative (power is injected into the public electricity grid).
An MQTT broker (available as an add-on for Home Assistant, and maybe for other home automation systems).
An energy meter providing measurements via the MQTT broker, or which is accessible as a Sensor in Home Assistant.
Some "always-on" computer for running the Energy Router script. You will need one to run the MQTT broker, anyway.
A home automation system interacting with the MQTT broker will be very helpful. This lets you control the operation of the whole thing. You will find some hints on how to do it with Home Asssistant in the Wiki.
The dimmer. You will need some basic electronic skills to assemble it yourself. You will also need to program its ESP8266 micro controller with ESPHome, which is also available as an add-on for Home Assistant.
Note (*): The preferred way for the energy meter communication is shown in the diagram. With Home Assistant, the Energy Router can also get energy meter readings from a Sensor state.
If you do not use a home automation system, and do not already have an MQTT broker running, you may want to have a look at another project, using less prerequisites: the Zero-Surplus-Dimmer.
The orange line corresponds to the grid power readings of the energy meter, the central horizontal line being zero.
The blue line corresponds to the power sent to the water heater (multiplied by -1). We see the regulation at work, as soon as the orange line reaches negative values.
For more information how to put this together, please see the Wiki.
